Marcos Antonio Matiello Fadini

Lethal and sub-lethal selectivity of fenbutatin oxide and sulfur to the predator Iphiseiodes zuluagai (Acari: Phytoseiidae) and its prey, Oligonychus ilicis (Acari: Tetranychidae), in Brazilian coffee plantations

Lethal concentration (LC) has been widely used to estimate pesticide toxicity. However, it does not consider the sub-lethal effects. Therefore we included the instantaneous rate of increase in association with LC to estimate population-level effects of the acaricides fenbutatin oxide and sulfur on the predator Iphiseiodes zuluagai and its prey, the phytophagous southern red mite, Oligonychus ilicis. The predator was 32.84x and 17.20x more tolerant to fenbutatin oxide and sulfur, respectively, than its prey, based on LC50 estimates obtained from acute concentration–mortality bioassays. The instantaneous rate of population growth in both mite species decreased with increasing acaricide concentration. Both acaricides provided effective control of O. ilicis at their recommended concentrations, but sulfur drastically compromised the predator populations quickly leading them to extinction due to the low reproductive potential of this species compared with its prey.

Controle de ácaros em sistema de produção integrada de morango

ABSTRACT Integrated production is an agricultural system thataims to produce good quality food, in conformity with therequirements of ambient sustainability, alimentary security andeconomic viability. Although there is not yet a developedintegrated system for strawberry production, techniques basedon biological control and induced responses to herbivory couldbe used to control phytophagous mites on strawberry. In thisreview we discuss these techniques within an integratedproduction context on strawberry. Key words : biological control, induced response, Fragaria . INTRODUCAO A atual demanda mundial por alimentoscertificados e isentos de residuos de pesticidas tempressionado o modelo convencional agricola aconstantes reavaliacoes de seus metodos de producao.Modelos de producao baseados em altos gastosenergeticos com pesticidas e fertilizantes estao sendoreavaliados quanto a sua sustentabilidade ao longo dotempo e a suas consequencias ao homem e ao meioambiente (FADINI & LOUZADA, 2001). Estatendencia tecnologica tem sido impulsionadaprincipalmente por pressao de grupos de consumidoresesclarecidos quanto aos problemas ambientaisdecorrentes de praticas agricolas convencionais. Oconsumidor tem, cada vez mais, interesse em conhecercomo os alimentos sao produzidos, se o modelo deproducao agricola utilizado esta causando impactosdanosos aos agroecossistemas e se existe algum riscode contaminacao do alimento (PESSOA et al.

Herbivoria de Tetranychus urticae Koch (Acari: Tetranychidae) induz defesa direta em morangueiro?

Plants of strawberry Fragaria x ananassa may present mechanisms of direct and indirect defenses against herbivores. Such defenses may influence behaviour and development of phythophagous mites and their natural enemies, thereby reducing herbivory rate. We tested the effect of pre-infestation of strawberry plants by Tetranychus urticae Koch on the development and reproduction of the mite species. Strawberry plants (cultivar IAC Campinas) were divided into two groups: plants without and plants with pre-infestation of T. urticae. The length of immature phases, the number of eggs per female and the survival of mites were not altered by the pre-infestation. These results may be associated to either the absence or low level of induced resistance of the cultivar IAC Campinas or perhaps the pre-infestation was insufficient to induce defenses. The reported resistance of this cultivar to T. urticae could be related to indirect defenses.

Demands and perspectives to acarology in Brazil

Sao escassos os relatos cientificos sobre demandas de pesquisa e perspectivas para a Acarologia no Brasil. Nesse trabalho, objetivou-se prospectar e caracterizar os estudos em acarologia ja realizados e identificar as principais demandas presentes e futuras em pesquisas em acarologia no Brasil. Para alcancar tais objetivos, realizaram-se revisoes bibliograficas das obras publicadas entre 1996 a 2006 e organizou-se o I Simposio Brasileiro de Acarologia. Os estudos com acaros de interesse medico-veterinario e agricola compoem o maior numero de artigos publicados, com destaque para as familias Ixodidae, Tetranychidae e Phytoseiidae. Esses estudos foram realizados, principalmente, na regiao Sudeste do Brasil. Dentre as principais demandas levantadas, destacaram-se o treinamento de taxonomistas para identificacao de especies de importância agricola e medico-veterinaria, o levantamentos de novas especies de acaros predadores para emprego no controle biologico aplicado, o estudo do papel dos acaros na ciclagem de nutrientes em ecossistemas e a mitigacao dos impactos negativos advindos do uso de acaricidas sinteticos. Palavras-chave: acaros, ciencia, tecnologia, pesquisa, ensino.

Períodos de ausência de presas e estabilidade do controle biológico do ácaro-rajado

The objective of this work was to access the biological parameters of the predator mite Phytoseiulus macropilis in the food absence for periods of one or more days. Data evaluated were: egg number per female per day; total number of eggs; longevity of females; and the offspring sex rate. Female in starvation for three or more days showed decrease in all biological variables. P. macropilis only will settle in the field if patch populations occupied by spider mite are not very distant from each other.

Distribuição espacial de ácaros fitófagos (Acari: Tetranychidae) em morangueiro

Many phytophagous mites can attack strawberry plants, Fragaria x ananassa, among them the southern red mite, Oligonychus ilicis McGregor, and the two-spotted spider mite, Tetranychus urticae Koch. They are found together feeding on the same plant on the upper and underside of the leaves, respectively. Here we studied the choice for feeding sites of O. ilicis and T. urticae on strawberry plants. The first hypothesis tested whether the feeding site choice would be related to the fitness of the species. The second hypothesis dealt whether the feeding site would be determined by the presence of a heterospecific mite. We evaluated the preference, biology and reproductive success of O. ilicis and T. urticae on the under and upper side surface of strawberry leaves infested or not by the heterospecific. O. ilicis preferred to stay on the upper side surface while T. urticae preferred the underside. The preference for the leaf surface correlated with the reproductive success of the species (measured by the intrinsic growth rate). The choice pattern of feeding sites did not alter when the choice test was applied using sites previously infested by heterospecific. Although O. ilicis and T. urticae, apparently, do not interact directly for feeding sites, there is a chance that the first species induces defenses in strawberry plant enabling to reduce the fitness of the second species. The possibility of those species stay together on strawberry plant increases the damage capacity to the culture.

Fitness costs associated with low-level dimethoate resistance in Phytoseiulus macropilis

Phytoseiulus macropilis Banks (Acari: Phytoseiidae) is an effective predator of tetranychid mites, but there are no data on its response to pesticides. We investigated the resistance of the predatory mite P. macropilis to the acaricides abamectin and dimethoate, and we examined the fitness costs associated with resistance. Two populations were tested: one from conventional cultivation and another from an area not commercially exploited. After the application of acaricides to the predator, we determined the lethal effects of the acaricides, the instantaneous rate of population increase (ri), the predation on Tetranychus urticae Koch (Acari: Tetranychidae) and its ability to locate prey in an olfactometer. P. macropilis exhibited resistance to dimethoate only. The low level of resistance (9.4x) of the predator did not affect their ability to locate prey. However, the dimethoate resistant population was not as effective in contatining prey population when in lower density and exhibited a more pronounced decrease of ri in the presence of this acaricide, due to the reduced oviposition of the predator, a likely consequence of the different genetic background of this population.

Efeito da profundidade de aplicação e da distribuição de inseticidas líquidos no controle de cupins de montículo em pastagens (Isoptera: Termitidae)

The efficacy of two depths was tested for the control of mound termites, Cornitermes sp. (Isoptera: Termitidae) using liquid a formulation of imidacloprid. Both devices were funnels constructed so as to differ only in the depth and distribution of the liquid within the termite nest. One of the devices was a standard funnel, whereas the other presented a longer tube perforated along its extension and closed in the outer end. Termites in mounds treated with the long funnel died faster than termites treated with the short funnel. It seems that the depth and distribution of the insecticide within termite nest was crucial for the efficacy of the control. We therefore recommend that control methods of termite in mounds should favor the use of applying devices which distribute better the insecticide within the nest.